This invention relates to an improved wiped-wall reactor, more particularly to a free-wheeling drag wheel driven by driven wheels in the reactor with a wiping means mounted on the driven wheels and actuated by the drag wheel so as to wipe the entire internal circumference of the cylindrical reactor, where the drag wheel generates a force to urge the wiping means against the internal circumference of the reactor, with the force generated by the drag of the pool of polymer on the drag wheel.
This invention is particularly adapted for use in a wiped-wall reactor wherein the driven wheels and drag wheel are mounted on a shaft eccentric with respect to the reactor horizontal axis. Such a configuration is shown and described in U.S. Pat. No. 3,617,225; see particularly FIGS. 9 and 10. Also see U.S. Pat. Nos. 3,469,948 and 3,476,522 for other types of wiped-wall reactors. U.S. Pat. No. 3,635,901 to Urgesi et al. uses centrifugal force and a fly weight to urge a wiping by distributor vane as shown in FIG. 5 of that patent. However, none of the prior art apparatus or processes were adequate.
The prior art discloses that a continuous wiping or wetting of fresh polymer helps to overcome formation of gel-like material due to formation of vinyl and polyvinyl compounds from polymer scission due to thermal degradation. Previously, these gels required periodic shutdown and flushing before the polymer being formed could pick-up gel-like deposits which would accumulate in said spaces in the reactor and fall into the pool of polymer.